1. Field of the Invention
This invention relates to information recording and reading techniques using modulated electromagnetic beam effect, wherein the read-write head and optical information carrier are displaced in relation to each other.
2. Description of the Related Art
Known in the art is an optical storage device (U.S. Pat. No. 4,404,571) employing a cylindrical information carrier. This known optical storage device has a very low density of information recording, since it uses only one optical head and has intervals between tracks.
The closest prior art, both technically and by the effect obtained, is an optical storage device (DE, A, 2 522 405) comprising an optical information carrier having reference tracks on the recording coating thereof, at least two optical heads which are optically connected with said optical information carrier, each said optical head being made of several optically connected elements, including a source of modulated coherent radiation, a movable optical element, a beam splitter, a photodetector having its first output connected to a repective input of an external control device, at least two autofocusing units, each having its input connected to a second output of the photodetector of a respective optical head, while the output of each autofocusing unit is kinematically connected to a movable optical element of its optical head, at least one tracking unit made as a disc, having its input connected to a third output of the photodetector.
This optical storage device is deficient in that its information recording density is insufficient because it is equipped with an inadequate tracking system which provides tracking of information tracks on the entire surface of the recording coating of the optical information carrier.